Is your check engine light on? If it is, or even if it is'nt try this trick:mattvw65 said:i have a 91 4.0 5 speed.
when on the gas fairly hard 3000 + rpm. the while jeep lurches like it just dropped the tranny. then back fires and dies. pull over to the side of the road wait less than a min. it will start back up and im on my marry way. just as long as i do not open her up. i just got back from a 5000 + mile trip. drove the jeep to florida from utah. and no problems the whole time. was out side of evenston wyoming. when this started. seems to be getting worse. :wow:
matt
http://4wheeldrive.about.com/gi/dynamic/offsite.htm?site=http://www.jedi.com/obiwan/jeep/dtc.html
I don't know for sure but my 96 XJ is doin the same thing and it turned out to be a couple of sensors. With this trick or w/ an OBD-II scanner you can see what your jeep is bitchin bout. Not sure if it will work on a 91 though?